An Electric cutter for cutting a concrete block and a tile has been well-known. The electric cutter has a drive unit such as an electric motor or an engine, a circular saw blade coupled to the shaft of the motor or engine, and a protection cover surrounding the outer periphery of the circular saw blade to prevent dust from scattering. When cutting is performed with such an electric cutter, it is difficult to prevent dust from scattering. Even if a workpiece is cut a little by the cutter, the generated dust may inevitably lower visibility at the working site. Therefore, a user is required to wear a dust-free mask and/or protective goggles whenever using the electric cutter.
Japanese Patent Application Publication No. 2002-046018 discloses an electric cutter that has a dust collecting hose attached to a protection cover of a main body. The dust-collecting hose is connected to an electric dust collector. The electric dust collector draws and collects the dust generated during the cutting operation.
Japanese Patent Application Publication No. 2004-058388 discloses a cutter having a base for moving on a workpiece while cutting operation, and a coil spring interposed between the base and a wheel cover. The coil spring urging the wheel cover away from the base, so that the cutter can collect the dust generated from the workpiece effectively.
With the conventional cutters, the scattering direction of the dust may change as the cutting depth by the blade. Therefore, it is difficult to collect all dust only by the wheel cover. For example, the dust generated by the cutting operation generally scatters almost parallel to the surface of the workpiece. When the dust collides with the wheel cover at almost right angles to the inner surface of the wheel cover, the dust is guided into the inlet port of the wheel cover. Thus, the larger the diameter of the blade, the faster the dust scatters from the blade in the tangential direction of the blade. If the scattering speed of the dust is higher, the dust may not be guided into the inlet port of the wheel cover after the dust collides with the inner surface of the wheel cover.
To solve the problem mentioned above, the sides of the wheel cover are required to be covered with another cover. When the sides of the wheel cover are covered with another cover, the entire blade would be covered, so that the user can hardly look at a cutting-start position or a cutting-end position. The user has to make a mark on a line of the workpiece extending from the peripheral surface of the base or the wheel cover, and aligning the cutting line with the mark, thereby confirming the position of the blade. Thus, it is difficult for the user to cut the workpiece at any desired position with high accuracy.
To enable the user to place the blade at any position precisely, the wheel cover may have an observation window in one side. Alternatively, the user may lift the base from the workpiece to confirm the position of the blade. In either case, the scattered dust still leaks through the observation window or the gap between the base and the workpiece to outside, which lowers the dust collecting efficiency.